sunpath z-up
3 messages in this thread
This is a question about Sunpath IPAS. If I import a model from
Autocad, north is apparently up, +Z is to the top of the screen.
Everything seems fine. I would have expected north on the left of
the screen to be -X. However, the sun does not rotate 90 degrees in
plan as I expected. It is clearly out of sync when viewed from the
front view port. I have never seen a problem like this posted before
therefore I must be doing something wrong. Have I got my Z's mixed
up? Any ideas?
As far as SunPath and 3DS are concerned, it seems that North is always towards
the top of the monitor in the Top viewport (ie +Z). Now, even though there are
options in the SunPath dialog to set the "direction" of North, it does NOT work
like what you would think, for example, if you had an ACAD drawing with north
to the right, imported the DWG and then told SunPath that +X is north, that
does NOT set +Z to West (as you would expect if you say, rotated the ACAD UCS
90 degrees to the right in plan view). Now, it's been a while since I
discovered that it was easier just to always import stuff with north oriented
to the top of the screen, so I don't guarantee my memory, but I think the
explanation is this: When you import from ACAD, where plan view is X,Y to 3DS
where it's X,Z 3DS makes the conversion of Z -> Y. You can tell 3DS in the
3DS.SET file to use some other axis convention (like X,Y). When you tell
SunPath that "north" is something other than +Z, it assumes you mean the same
thing as when you change the 3DS coordinate system in the SET file — in other
words, you're not telling it where PLAN NORTH is, you're telling it where 3DS
COORDINATE NORTH is, so it assumes you're telling it a whole different
coordinate systme from X,Z plan.
Does this make ANY sense?<g>
Dave
Robert:
>> This is a question about Sunpath IPAS. If I import a model from Autocad,
>> north is apparently up, +Z is to the top of the screen.
I just got back from Thanksgiving (home in Penn State-land, man those people
know how to go crazy about a football team! There are over 5,000 of them
signed up with formal tour groups to come out here for the Rose Bowl, not
including those coming out on their own!)
As I was saying (before I so rudely interrupted myself) AutoCAD and 3DS use a
different coordinate system for X, Y, and Z, as you noticed. There are two
options for aligning the two. One is just to select a different orientation in
the dialog box for SunPath (that's why it asks). The other is to change the
orientation permanently in your 3DS.SET file. Both will work, the setting in
the SunPath dialog is easier unless you are running it often.
Let me know if you have any other questions about it!
Greg Pyros